1. Technical Field
The present invention relates generally to an electrosurgical instrument and, more particularly to an electrosurgical pencil having drag sensing capabilities.
2. Background of Related Art
Electrosurgical instruments have become widely used by surgeons in recent years. Accordingly, a need has developed for equipment that is easy to handle and operate, reliable and safe. By and large, most electrosurgical instruments typically include a hand-held instrument, or pencil, which transfers radio-frequency (RF) electrical energy to a tissue site. The electrosurgical energy is returned to the electrosurgical source via a return electrode pad positioned under a patient (i.e., a monopolar system configuration) or a smaller return electrode positionable in bodily contact with or immediately adjacent to the surgical site (i.e., a bipolar system configuration). The waveforms produced by the RF source yield a predetermined electrosurgical effect known generally as electrosurgical fulguration.
In particular, electrosurgical fulguration comprises the application of electric spark to biological tissue, for example, human flesh or the tissue of internal organs, without significant cutting. The spark is produced by bursts of radio-frequency electrical energy generated from an appropriate electrosurgical generator. Generally, fulguration is used to dehydrate, shrink, necrose or char the tissue. As a result, the instrument is primarily used to stop bleeding and oozing. These operations are generically embraced by the term “Coagulation”. Meanwhile, electrosurgical cutting includes the use of the applied electric spark to tissue which produces a cutting effect. Electrosurgical searing includes utilizing both electrosurgical energy and pressure to melt the tissue collagen into a fused mass.
As used herein the term “electrosurgical pencil” is intended to include instruments which have a handpiece which is attached to an active electrode and are used to coagulate, cut and/or sear tissue. The pencil may be operated by a handswitch or a foot switch. The active electrode is an electrically conducting element which is usually elongated and may be in the form of a thin flat blade with a pointed or rounded distal end. Alternatively, the active electrode may include an elongated narrow cylindrical needle which is solid or hollow with a flat, rounded, pointed or slanted distal end. Typically electrodes of this sort are known in the art as “blade”, “loop” or “snare”, “needle” or “ball” electrodes.
As mentioned above, the handpiece of the pencil is connected to a suitable electrosurgical source (i.e., generator) which produces the radio-frequency electrical energy necessary for the operation of the electrosurgical pencil. In general, when an operation is performed on a patient with an electrosurgical pencil, electrical energy from the electrosurgical generator is conducted through the active electrode to the tissue at the site of the operation and then through the patient to a return electrode. The return electrode is typically placed at a convenient place on the patient's body and is attached to the generator by a conductive material.
When using electrosurgical instruments in an operation, the active electrode may be rendered less efficient if the tissue distorts or encounters inconsistencies in the tissue. These instances are sensed as a change in the tension required to pass the electrode through the tissue (i.e., “drag”).
Also, when using electrosurgical instruments in an operation, the tissue tends to to char during the surgical procedure and adhere to the active electrode. When the active electrode is an electrosurgical blade, the charred tissue can in some instances effect the overall performance of the electrosurgical blade. Performance degradation of the blade may reduce the effectiveness of the instrument during the operation. For example, a build up of charred tissue on the active electrode may effect cutting efficiency of the blade. As a result, the surgeon may find it necessary to increase the electrical current to the electrosurgical blade in order to compensate for the degradation of the cutting blade. This raises the possibility that the tissue will be more easily and rapidly charred when contacting the tissue.
Another concern resulting from the build up of charred tissue on the active electrode is that the charred tissue can fracture and contaminate the surgical site which may delay the overall healing process. The build up of charred tissue on the active electrode may also increase drag (i.e., the amount of resistance the body tissue exhibits during cutting). Drag may distort the tissue and consequently alter anatomical relationships which can effect proper suturing, possibly delay healing, and result in more visible scarring.
Accordingly, the need exists for an electrosurgical pencil which includes drag sensing capabilities to readily alert the operator when the drag force acting on the electrosurgical blade has surpassed a predetermined threshhold level and/or the electrosurgical blade has been displaced beyond a predetermined acceptable level.